248 lines
6 KiB
C
248 lines
6 KiB
C
/*
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* Copyright (C) 2014 Sergey Senozhatsky.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/wait.h>
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#include <linux/sched.h>
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#include <linux/cpu.h>
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#include <linux/crypto.h>
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#include "zcomp.h"
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static const char * const backends[] = {
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"lzo",
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#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
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"lz4",
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#endif
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#if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
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"lz4hc",
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#endif
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#if IS_ENABLED(CONFIG_CRYPTO_842)
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"842",
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#endif
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#if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
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"zstd",
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#endif
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NULL
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};
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static void zcomp_strm_free(struct zcomp_strm *zstrm)
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{
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if (!IS_ERR_OR_NULL(zstrm->tfm))
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crypto_free_comp(zstrm->tfm);
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free_pages((unsigned long)zstrm->buffer, 1);
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if (zstrm->tmpbuf) {
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free_pages((unsigned long)zstrm->tmpbuf, 1);
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zstrm->tmpbuf = NULL;
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}
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kfree(zstrm);
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}
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/*
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* allocate new zcomp_strm structure with ->tfm initialized by
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* backend, return NULL on error
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*/
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static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
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{
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struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
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if (!zstrm)
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return NULL;
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zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
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/*
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* allocate 2 pages. 1 for compressed data, plus 1 extra for the
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* case when compressed size is larger than the original one
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*/
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zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
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zstrm->tmpbuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
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if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer || !zstrm->tmpbuf) {
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zcomp_strm_free(zstrm);
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zstrm = NULL;
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}
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return zstrm;
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}
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bool zcomp_available_algorithm(const char *comp)
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{
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int i;
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i = __sysfs_match_string(backends, -1, comp);
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if (i >= 0)
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return true;
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/*
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* Crypto does not ignore a trailing new line symbol,
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* so make sure you don't supply a string containing
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* one.
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* This also means that we permit zcomp initialisation
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* with any compressing algorithm known to crypto api.
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*/
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return crypto_has_comp(comp, 0, 0) == 1;
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}
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/* show available compressors */
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ssize_t zcomp_available_show(const char *comp, char *buf)
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{
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bool known_algorithm = false;
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ssize_t sz = 0;
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int i = 0;
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for (; backends[i]; i++) {
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if (!strcmp(comp, backends[i])) {
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known_algorithm = true;
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sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
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"[%s] ", backends[i]);
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} else {
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sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
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"%s ", backends[i]);
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}
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}
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/*
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* Out-of-tree module known to crypto api or a missing
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* entry in `backends'.
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*/
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if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
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sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
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"[%s] ", comp);
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sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
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return sz;
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}
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struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
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{
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return *get_cpu_ptr(comp->stream);
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}
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void zcomp_stream_put(struct zcomp *comp)
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{
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put_cpu_ptr(comp->stream);
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}
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int zcomp_compress(struct zcomp_strm *zstrm,
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const void *src, unsigned int *dst_len)
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{
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/*
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* Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
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* because sometimes we can endup having a bigger compressed data
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* due to various reasons: for example compression algorithms tend
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* to add some padding to the compressed buffer. Speaking of padding,
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* comp algorithm `842' pads the compressed length to multiple of 8
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* and returns -ENOSP when the dst memory is not big enough, which
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* is not something that ZRAM wants to see. We can handle the
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* `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
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* receive -ERRNO from the compressing backend we can't help it
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* anymore. To make `842' happy we need to tell the exact size of
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* the dst buffer, zram_drv will take care of the fact that
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* compressed buffer is too big.
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*/
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*dst_len = PAGE_SIZE * 2;
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return crypto_comp_compress(zstrm->tfm,
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src, PAGE_SIZE,
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zstrm->buffer, dst_len);
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}
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int zcomp_decompress(struct zcomp_strm *zstrm,
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const void *src, unsigned int src_len, void *dst)
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{
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unsigned int dst_len = PAGE_SIZE;
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return crypto_comp_decompress(zstrm->tfm,
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src, src_len,
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dst, &dst_len);
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}
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int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
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{
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struct zcomp *comp = hlist_entry(node, struct zcomp, node);
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struct zcomp_strm *zstrm;
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if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
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return 0;
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zstrm = zcomp_strm_alloc(comp);
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if (IS_ERR_OR_NULL(zstrm)) {
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pr_err("Can't allocate a compression stream\n");
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return -ENOMEM;
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}
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*per_cpu_ptr(comp->stream, cpu) = zstrm;
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return 0;
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}
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int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
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{
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struct zcomp *comp = hlist_entry(node, struct zcomp, node);
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struct zcomp_strm *zstrm;
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zstrm = *per_cpu_ptr(comp->stream, cpu);
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if (!IS_ERR_OR_NULL(zstrm))
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zcomp_strm_free(zstrm);
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*per_cpu_ptr(comp->stream, cpu) = NULL;
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return 0;
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}
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static int zcomp_init(struct zcomp *comp)
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{
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int ret;
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comp->stream = alloc_percpu(struct zcomp_strm *);
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if (!comp->stream)
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return -ENOMEM;
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ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
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if (ret < 0)
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goto cleanup;
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return 0;
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cleanup:
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free_percpu(comp->stream);
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return ret;
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}
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void zcomp_destroy(struct zcomp *comp)
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{
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cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
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free_percpu(comp->stream);
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kfree(comp);
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}
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/*
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* search available compressors for requested algorithm.
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* allocate new zcomp and initialize it. return compressing
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* backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
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* if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
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* case of allocation error, or any other error potentially
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* returned by zcomp_init().
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*/
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struct zcomp *zcomp_create(const char *compress)
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{
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struct zcomp *comp;
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int error;
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if (!zcomp_available_algorithm(compress))
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return ERR_PTR(-EINVAL);
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comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
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if (!comp)
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return ERR_PTR(-ENOMEM);
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comp->name = compress;
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error = zcomp_init(comp);
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if (error) {
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kfree(comp);
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return ERR_PTR(error);
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}
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return comp;
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}
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